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Time and Change. Chapter 4. Section 1 Earth’s History. Objectives: Describe the origin and early history of the earth Describe the processes of change on the earth’s surface Infer how different sedimentary rock forms Communicate in a diagram how processes of surface change are related. - PowerPoint PPT Presentation
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Time and Change
Chapter 4
Section 1 Earth’s History
• Objectives:– Describe the origin and early history of the
earth– Describe the processes of change on the
earth’s surface– Infer how different sedimentary rock forms– Communicate in a diagram how processes of
surface change are related
Skills Warm-up
• Time To Change– Look around the classroom and outside the
classroom.– Make a list of 10 objects or conditions that
don’t seem to change day to day.– How could they change and how long would it
take?
Earth’s History• How will you change over
the next few years? Ten years?
• How will your family and community change in the next few years?
• How will the earth change in the next few years?
Earth’s History• Compared to changes in the
______ _______, changes in the earth are ________ and _____________
• We usually think of the earth and its features as ___________ and ___________
• But they are not…….
Earth’s History
• Things that change – ___________– ___________– ___________– ___________
• They only change much more slowly, over enormous periods of time!!
Age of the Earth• Earth is
_________________• If you compare the age of
the earth to a 24 hour day, how old would you be?
• You would not be hours, minutes or even seconds old!
• Even at 100 years old, your life would only be ________ __ ___ ____________
Earth’s history is very long!You have to think about it in geologic time
Origin of the Earth
• 1. ~5 byo – cloud of _______ ________ _________.• 2. The matter was drawn to center by _______. The
center increased in _________, and grew __________________
• 3. _______ ________– light and heat was released. The sun was born.
• 4.Leftover matter began to clump and each clump became a _________.
Earth’s Early History• First billion years, the hot
surface ________ __________________
• Volcanoes ________ and gasses formed an ____________
• ________ __________, turned to liquid, and fell to earth as rain
• Eventually an ________ covered earth’s surface
Earth’s Early History• 3.8 million years ago, the
first small ___________ formed from _________ ___________– The first _______
_______came into being in the ________
– Some of these beings were able to produce _________ as a part of what process????
Earth’s Early History
• 2 million years ago the earth looked like it does today – It had __________ and
__________ and ________
– The atmosphere contained ________ and the sun’s energy created ________ ________
– But no ______ __________
Surface Changes
• Earth is still continuing to _________
• These changes are _______ and they follow _________ __________
• What are they??
______________ - when rock is broken down into smaller
particles• __________ _________
occurs through direct contact with atmospheric conditions, such as _____, ________, _______ and __________.
• _________ _________-involves the direct effect of atmospheric or biologically produced ___________
___________ – when small particles are carried away
• ______, ______ , _____, flowing ______, and ______ can all erode rock particles
• ___________ – the particles that are carried away
• Weathering/Erosion are _______ processes that cause ________ changes
• “______________” processes• __________ can disappear
and __________ can form
Surface Changes• ________ – the buildup
of eroded sediment– Occurs because of
_________• Where are particles
deposited?– Bottoms of _______
and _________, and ______ ________
• “___________” process• Occurs _______, all the
time
Sedimentary Rock• __________ from years of
weathering, erosion and deposition builds up, forming ___________ _________
• ______ layers form on top of ______ layers
• __________ of overlying sediment __________ lower layers
• __________ cement sediment together
• Sediments become ___________ _______
• Lowest layers are the ______
Uplift
• What would happen if weathering, erosion, deposition, and the formation of sedimentary rock were the only processes shaping earth??
Uplift
• Process by which parts of earth’s crust are ________ above others, forming _________/________
• There are always new, elevated __________ to be ______ ________
Skills Warm-up
• On Ice– When sheets of ice expand and advance from
the poles, much of earth’s water is frozen in ice.
– What do you think might happen to ocean levels?
– How might this effect shoreline erosion?
Changes in Life• _____________ are an
important part of earth’s history
• Living things __________ and ________ along with the earth
• _________ – inherited traits of a species change and new species _________
• Organisms that lived in the past left __________ of their _____________
• What are they called???
Changes in Life• _________– ______ or
______ of an organism that lived in the past.
• Organism was ________ in _________, became part of a ________ over time.– A fossil is therefore as old as the
rock of which it is a part.
• What have scientists learned from fossils?
• Living things _______ _________ over time (evolution)
• Many organisms are now ________
Fossils• Found in the _________• Preserved ancient ________ of _________• _________ fossils looked like organisms that
were alive – others did ______• The fossil record shows animals that were
preserved by being buried in the _______, _____ ______ or ______ _______
• Sedimentary rock-layers of sediment cover up the animals and _________ the remains
FOSSIL RECORD-INFORMATION OF PAST FORMS OF LIFE
• Tells of major changes in the ________ ________ of earth
• _____ __________ in Arizona – Coastline changes
• ______ __________ in N. America – Warmer climate
• What does a ____________ study?
FORMATION OF FOSSILShttp://www.pbs.org/wgbh/evolution/library/04/3/l_043_01.html
• Most are found in sedimentary rock –sediment forms when sand and silt from water settle to the bottom of a body of water
• Animals and plants that die in the water are compressed into rock by pressure from the water
FORMATION OF FOSSILS
• Bones and teeth may be preserved on land by shifting sand, mud, or volcanic ash.
• Footprints or soft tissue can be preserved if they fill with dust or ash. They are then covered by other materials and harden.
FORMATION OF FOSSILS• Petrification can occur when remains are
covered with water
• Dissolved minerals from the water replace the decaying tissues and harden
James Hutton• Scottish scientist – 1700’s• He observed that __________ were ____
_____than anyone had thought• He saw that earth’s ________ had changed
_________ over a long period of time• _______________________________ – the laws
of nature do not change over time• So, the _______ _________ that shaped the
earth in the past are still at work today• Gave birth to the modern science of
___________ and changed the human ________ __ ________
Changes in Climate
• Throughout earth’s history, the _________ ________ due to ____________ causes
• Sometimes the planet was ______ ___ ______
• Other times it was _____ and _____
• During cold times, the polar ice caps __________ ___ ______
• Huge sheets of ice spread from the poles to the ___________ _____________
Are Humans Changing the Climate?
• _______ _________– cities cause changes in temperature
• City temperatures are slightly _________ than surrounding areas
Are Humans Changing the Climate?
• Cutting down large areas of forest in ________ ________ changes ________ __________
• Deforested areas hold less ____________ – more rainwater drains to _________
• Less water ____________ into clouds – leads to _____ ____________
Are Humans Changing the Climate?
• Global changes – ________ ________
• Burning of _________ _________for energy increases the amount of _______ in the atmosphere
• Causes small __________ in the average __________ of the earth
Section 2Geologic Time Scale
• Objectives:– Explain how scientists determine the relative age
of sedimentary rocks– List the order of events that may result in an
unconformity being formed– Describe the major divisions of the geologic time
scale– Infer the relationship between the layering of
sedimentary rock and the geologic time scale
Skills Warm-up
• The Time of Your Life– Make a timeline showing the major events of
your life (so far).– Divide the timeline into stages based on these
events.– How many stages did you make? How did you
decide what was a separate stage?
Time Record
• How have scientists learned enough about the earth’s history to divide it into stages?
• How do they find out about events that took place millions or billions of years ago?
Time Record in the Rocks
• The rocks of the earth’s _________ hold all the __________.
• Scientists just had to learn how to “read” the ________ ___ _______ preserved in the rocks.
Rock Layering
• _______ _______ ________ provide evidence of past events– Ex) volcanic ash
layer– Ex) Layer with
marine fossils
Rock layers are stacked according to ______________ rocks are under _________ rocks.Therefore, drilling through the layers is like going _______ __ _____(as long as layers weren’t turned upside down by ___________).
RELATIVE AGE
To determine the ______ of a layer of sedimentary rock, or a fossil in such a layer, compare its ________ to other rock layers _________ it
You’d say, “This layer is younger than this layer” or “This layer is older than this layer”
This doesn’t give you an actual age in years, but an age “__________” to the other layers
RELATIVE AGE• Relative positioning –
________ _____ _________• For example :
– Layer of sedimentary rock formed from volcanic ash, beneath a layer of sedimentary rock deposited in a shallow sea.
– What can you infer from this evidence?
• The sea formed ________ the volcano erupted.
Relative Dating
• _________ _________ means identifying which rock units formed first, second, third, and so on
• It tells us the _________ in which events occurred, ______ how long ago they occurred.
Nicolaus Steno 1636-1686
• Danish __________• Credited with
describing a set of geologic observations that are the basis of ________ _________
Skills Warm-up
• Something Old …….– Think of something living or non-living that is
over 100 years old.– What evidence do you have that the object is
old?– How does it differ from a similar object that is
much newer?
Key Principles of Relative Dating1. ____ ______________ – states that in an __________
sequence of sedimentary rocks, each bed is ________ than the one above it and ____________ than the one below it.
2. ________________________________ – layers of sediment are generally deposited in a horizontal position.
3. _____________________________ – states that a _______ or ________ intrusion is __________ than the rock layers affected.
Unconformity• _________ in layering of rock• Layers that were _______ are covered
by horizontal layers.• Line between them – _____________ – Represents a break in ________
Absolute Age
• Determining the _________ ______of rocks, in _________• Obtained through _____________ __________
Radiometric Dating
• Radiometric dating is a technique used to date materials
• It compares the amount of a naturally occurring ______________ and its _____ _________, in samples
• The method uses known decay rates – ________ _________
Absolute Age
• It is the ______ source of information about the ______ of rocks and other geological features, including the age of the ________ itself
• Radiometric dating methods are used to establish the ________ _______ _________
Geologic Time Scale
• The geologic time scale is used by scientists to map the _______ and __________ between events that have occurred during the _______ of the Earth.
• It __________ estimates of the age of geological formations as provided by:• ___________________________________• direct evidence of _________ ___ _______in the rock
record as assembled by ____________
GEOLOGICAL TIME SCALE
Review Questions
• 1. How are sediments that become rock layers deposited?
• 2. How do layers become tilted?• 3. If folded rock layers erode, what happens to the
unexposed portion?• 4. If new sediments are deposited over the eroded
layers, what do earth scientists know?• 5. What is the difference between the relative age
and absolute age of rock layers?
Divisions of Geologic Time
• Scientists have divided geologic time into _______ large units called _______
• Era– _________ _________of geologic time– Each of the four eras cover a ___________
_________in Earth’s history
Precambrian Era• _______ and ___________ era in Earth’s history.• Includes all events from ________ ____________(6 billion
years ago) to a time about _______ million years ago• Ended when ______ and ____________ life forms appeared
– _________________
Paleozoic Era
• The _____ _________ ________following the end of the Precambrian Era
• _______ and ___________ began to live on land• Ended when many organisms became extinct
Mesozoic Era 245 – 66 MYA• The time of ____________• Most of the Earth had a _______,
________ climate.• Ended when the dinosaurs and
many other organisms ______ _______
• Extinctions might have occurred from an ____________
• Mass extinctions
Cenozoic Era• Our _______________ era
(66 MYA until now)• Climate has become much
________ ____ ________• Several _____ _______have
come and gone• Humans have been around
for a _______ part of this era
Periods and Epochs
• __________ units of time• Periods are smaller divisions
of eras, and epochs are smaller divisions of periods.– Era period epoch
• Why are these divisions more useful than stating a particular era?
• Ability to be ______ __________when dating something.
Telling Time - The Earth is the “ultimate clock”
• How do we define a Day? • The amount of time it
takes the Earth to ___________________
• How do we define a Year?
• The amount of time it takes the Earth to __________________
Telling Time - The Earth is the “ultimate clock”
• The earth’s ____________ define how people ___________ and __________ time.
• How would your life be different if the earth took ½ as long to complete one journey around the sun?
• What about your life would change if one rotation of earth around its axis took twice as long?
• The earth’s ______ ___ _____________doesn’t change, so are lives stay the same.